/**
 * utils/process-tracker.ts – Registry of spawned child processes.
 *
 * Tracks PIDs of child processes spawned by the agent (bash commands, scripts)
 * so they can be force-killed when an agent turn is cancelled or the
 * application is shutting down.
 *
 * Consumers:
 *   - tools/tracked-bash.ts registers/unregisters PIDs around each bash exec.
 *   - agent-pool.ts calls killTrackedProcesses() when aborting an agent run.
 *   - runtime.ts calls killTrackedProcesses() on graceful shutdown.
 */

import { spawn } from "child_process";

import { createLogger, debugSuppressedError } from "./logger.js";

const log = createLogger("process-tracker");

/** Internal record for a tracked child process. */
type TrackedProcess = {
  pid: number;
  createdAt: number;
};

/** Map of PID → TrackedProcess for all currently tracked child processes. */
const tracked = new Map<number, TrackedProcess>();

/** Add a PID to the tracker. Called by tracked-bash.ts after spawning. */
export function registerProcess(pid: number): void {
  if (!Number.isFinite(pid)) return;
  tracked.set(pid, { pid, createdAt: Date.now() });
}

/** Remove a PID from the tracker. Called by tracked-bash.ts when a process exits. */
export function unregisterProcess(pid: number): void {
  tracked.delete(pid);
}

/** Return the list of currently tracked PIDs. Used for diagnostics. */
export function listTrackedProcesses(): number[] {
  return [...tracked.keys()];
}

/**
 * Kill a process and its entire process tree.
 * On Unix, sends SIGKILL to the process group (-pid); falls back to
 * killing just the PID if the group kill fails.
 * On Windows, uses `taskkill /F /T`.
 */
export function killProcessTree(pid: number): void {
  if (!Number.isFinite(pid)) return;
  if (process.platform === "win32") {
    try {
      spawn("taskkill", ["/F", "/T", "/PID", String(pid)], {
        stdio: "ignore",
        detached: true,
      });
    } catch (err) {
      debugSuppressedError(log, "Failed to invoke taskkill for a tracked process tree.", err, {
        operation: "process_tracker.kill_process_tree.taskkill",
        pid,
      });
    }
    return;
  }

  try {
    process.kill(-pid, "SIGKILL");
  } catch {
    try {
      process.kill(pid, "SIGKILL");
    } catch (err) {
      debugSuppressedError(log, "Failed to SIGKILL a tracked process after process-group termination failed.", err, {
        operation: "process_tracker.kill_process_tree.kill_pid",
        pid,
      });
    }
  }
}

/**
 * Kill all tracked processes and clear the tracker.
 * Returns the number of processes that were killed.
 * Called by agent-pool.ts on abort and runtime.ts on shutdown.
 */
export function killTrackedProcesses(): number {
  const pids = [...tracked.keys()];
  for (const pid of pids) {
    killProcessTree(pid);
    tracked.delete(pid);
  }
  return pids.length;
}